Ametropia, such as myopia, hyperopia, or astigmatism, is an abnormal refractive condition of eyes in which images fail to focus upon the retina. A user can choose eyeglasses or Laser in Situ Keratomileusis (LASIK) surgery to correct ametropia. However, the effect of ametropia correction cannot be predicted in advance whether the user chooses eyeglasses or LASIK surgery. The user may be not satisfied with the effect of the ametropia correction. Thus, when the user chooses eyeglasses, the eyeglasses need to be modified, which increases the manufacturing cost. When the user chooses the LASIK surgery, which uses an excimer laser to cut or reshape the cornea, the cornea after surgery is often not amenable to further surgery.